Conventional phenolic, epoxide and unsaturated polyester resins used to make such duromer components are highly stable and exhibit a lasting high-temperature resistance up to over about 200.degree. C. However, these advantageous properties are limited due to the considerable brittleness of these thermosetting plastics--especially at temperatures below about 0.degree. C.
Better resistance to cold at temperatures down to minus 40.degree. C. can be achieved by using thermosetting plastics, for example, polypropylene reinforced with glass-fiber mat. A significant disadvantage of these materials is poor dimensional stability at temperatures above about 130.degree. C. Another disadvantage is the high pressures, e.g., up to 1000 tons/m.sup.2 needed for molding such materials which results in high tool and molding costs, particularly in the manufacture of large-volume components.
It has proven difficult to make duromer components that have the physical properties specified by automobile manufacturers with conventional resins In particular, it has been difficult to obtain high notch impact resistance at temperatures down to about minus 40.degree. C. and dimensional stability up to about 250.degree. C. (particularly significant for molded components located close to a motor). Improvements in the molding materials for making duromer components have been sought, in particular, deformability at molding pressures, which lie at about 100 t/m.sup.2 or less; improved storage stability even when stored and transported for longer periods of time (improved availability of, premanufactured "masterbatch" liquid or pasty molding material mixture in larger quantities); very low viscosity of the molding materials to provide considerable leeway for adding fillers (thus providing a considerable range for the mechanical properties of the molded articles to be manufactured); and lasting bondability of the masterbatch with other polyurethane materials during and/or after molding.